evidently formed as a sediment at the bottom of the secondary 
sea. These Gausses, the highest portion of which rise 1,200 
metres above the sea, have, in the course of time become fur- 
rowed by canons 400-500 m. in depth. There are four princi- 
pal Gausses and numerous smaller ones. These four, com- 
mencing at the North, are : the Causse Sauveterre, which is- 
the least sterile of all ; the Gausse Mejean, the most arid, ele- 
vated and isolated, having an area of 400 sq. kil., and united 
to another Causse only by an isthmus, which is, in some cases, 
not more than 10 m. wide; the Gausse Noir, which is the 
smallest and most picturesque of the large Gausses ; and the 
Gausse Larzac, largest of all, with an area of 1,400-1,500 sq, 
kil. All these Gausses are bare, dreary, monotonous deserts, 
without water and almost without inhabitants. The rivers 
that separate them have no above-ground affluents, but are fed 
by powerful springs and streams that flow from the junction of 
the limestone with the clay beneath, at the level of the bottom' 
of the gorges. The rains penetrate the limestone at apertures 
which are called avens, sink until they reach the bed of clay andi 
have underground courses sometimes of considerable length. 
Exploration of the caverns is, however, very difficult, and, in- 
deed, impossible, except to those provided with proper appar- 
atus. M. Martel traced the course of a stream, the disappear- 
ance of which had long been a problem to the natives, and' 
discovered two caverns, one of which, Dargilan, has a 
length of 2800 m. with many large halls, one 190 m. long, and 
is, in many respects, a rival to the celebrated Grotto of Adels- 
berg, especially as it has the finest stalactites in Europe. 
The finest gorge is that of the Tarn, which for 80 kilo, flows 
in the depths of a canon, the walls of which have a mean 
height of 500 m. One of the greatest wonders of the region 
is Montpellier-le Vieux, a promontory of triangular shape 
upon the Causse Noir, above the valley of the Doubre which 
is here 400 m. deep. At this spot 1000 hectares are covered 
with what seems like the ruins of a city with its streets,, 
squares, monuments, etc. M. Martel's description recalls the 
Garden of the Gods and other spots in Colorado. 
